Lymphoma is a blood cancer that develops in the lymphatic system — the network of vessels, nodes, and organs that helps your body fight infections and remove excess fluids. It represents approximately 50% of all blood cancer diagnoses each year, making it the most common form of blood cancer.
In lymphoma, abnormal lymphocytes (a type of white blood cell) multiply uncontrollably and collect in your lymph nodes and other lymphatic tissues. Unlike normal lymphocytes that help fight infection, these cancerous cells do not function properly and eventually crowd out healthy immune cells.
Lymphoma is divided into two main categories: Hodgkin Lymphoma and Non-Hodgkin Lymphoma. Hodgkin Lymphoma comprises about 12% of all lymphoma cases and is distinguished by the presence of Reed-Sternberg cells — large, abnormal cells visible under the microscope. According to ASH, Hodgkin Lymphoma is considered one of the most curable types of cancer, thanks to decades of research that transformed it from a fatal disease to a highly treatable one.
Non-Hodgkin Lymphoma (NHL) accounts for the majority of lymphoma cases and includes over a dozen subtypes. Most NHL cases involve B-cell lymphomas, which are further classified as high-grade (fast-growing, aggressive) or low-grade (slow-growing, indolent). T-cell lymphomas, named after the cancerous T-lymphocytes involved, are less common but can be more challenging to treat.
Risk factors for lymphoma include advanced age, male gender, autoimmune diseases, HIV/AIDS, exposure to pesticides, a diet high in fat and meat, and family history of lymphoma. However, lymphoma can develop in anyone, and no definitive preventive measures exist because the exact causes remain unknown.
The most common symptom is swollen lymph nodes in the neck, armpits, or groin that are typically painless. Other symptoms include unexplained fever, persistent fatigue, unintentional weight loss, drenching night sweats, difficulty breathing, chest pain, and skin itching or rashes. These symptoms can be subtle and are often attributed to other conditions, so persistent symptoms warrant medical evaluation.
Diagnosis requires a lymph node biopsy — removing part or all of an affected lymph node for microscopic examination. This is the definitive test that distinguishes lymphoma from other conditions. Blood tests and bone marrow biopsies provide additional information about disease extent. Imaging studies including CT scans and PET scans are crucial for staging — determining how far the disease has spread, which directly influences treatment planning.
Treatment for lymphoma has advanced significantly. Options include chemotherapy, combined chemotherapy and radiation therapy, immunotherapy, and stem cell transplantation. CAR T-cell therapy — a form of immunotherapy where a patient's own immune cells are modified to target cancer cells — has emerged as a promising treatment for certain types of NHL that have not responded to other treatments. Clinical trials continue to expand treatment options and improve outcomes for lymphoma patients.